This invention relates to connection means for connecting adjacent channel sections of a scraper-chain conveyor or adjacent sections of a winning machine guide, and to a retaining element for such connection means.
A variety of devices for connecting the individual channel sections of scraper-chain conveyors are known. Such devices normally resist tensile forces which tend to draw the ends of thc channel sections apart, and allow some angular mobility between the channel section ends. The conncction devices are often subjected to very high forces during operation, not only the tensile forces which they are designed to resist but also buckling forces tending to displace the conveyor ends laterally and/or vertically. Primarily, the lateral forces occur when the conveyor is shifting up to follow the mineral winning progress. This is usually accomplished by means of rams which shift individual lengths of the conveyor in the so-called "snaking" movement. The vertical forces usually occur when a mining machine supported on the conveyor is moved, for example, along the mineral face. Where the floor of the mine working is uneven, these lateral and vertical forces can increase substantially.
One known form of device for connecting the individua- channel sections of a scraper-chain conveyor is constituted by a coupling member in the form of a shank provided at each end with an enlarged head portion. The coupling member is introduced into aligned apertures in coupling elements which are welded onto the channel section ends. The coupling member is received within the aligned apertures with a predetermined amount of axial play. One head portion of the coupling member is provided with an axially-extending fastening member which engages behind a complementary fastening member provided on one of the channel sections. The other head portion of the coupling member is provided with a pair of shoulders which cooperate with complementary recesses provided in the coupling element of the other channel section. The coupling member can be introduced into the apertures obliquely from the side, and is prevented from falling out laterally by the fastening member and the shoulders engaging respectively with said complementary fastening member and said complementary recesses. A retaining element in the form of a metallic C-shaped clip is positioned adjacent to said other head portion of the coupling member to prevent axial movement of the coupling member by filling up the space available for said predetermined amount of axial play. Thus, the coupling member cannot move along the aligned apertures so that its fastening member and shoulders move out of engagement with their respective complementary fasteners. The coupling member is, therefore, safely held in position under all normal load conditions, particularly under the loads imposed by angling of the channel sections. (See DE-OS 2 636 527).
Unfortunately, it has been found that resilient clips of this type are subjected to considerable forces in the course of underground mining operations, and these forces may lead to the permanent deformation and damage of the clips. Such damaging forces can arise, for example, when coal dust collects in the pockets that accommodate the clips, the dust becoming relatively firmly briquetted in the pockets, so that the inherent limited degree of play within the pockets is reduced. Moreover, during underground operations, the resilient clips suffer quite considerable corrosion, which affects their operational efficiency, and hence reduces the reliability of the connection means.
Connection means of this type are also used for connecting the sections of a winning machine guide (for example a plough guide) which is built onto the channel sections of a scraper-chain conveyor.
Instead of metallic resilient clips, it is also known to use clips made of a resilient material such as rubber, and to surround this material with a wear-resistant jacket. The resilient material has a rigid filler embedded therein to form a resilient, but firm, core. Unfortunately, retaining elements of this type are relatively costly to manufacture, and are also subject to corrosion when use is made of a metallic jacket. (See DE-OS 2 826 023).
The aim of the invention is to provide a retaining element for connection means of the type described above, the retaining element being easy and inexpensive to manufacture, whilst having greater operational reliability.